System and Method to Facilitate Treatement and Sand Control in a Wellbore

ABSTRACT

A technique provides a multi-stage well treatment system having a plurality of packers and a plurality of flow valves. The multi-stage well treatment system can be moved downhole in a wellbore and actuated to isolate a plurality of sections along the wellbore for treatment. The system and methodology enable treatment, e.g. fracturing, of select sections via the flow valves, while also enabling use of the flow valves to establish a permeable, stabilized pack surrounding each flow valve.

BACKGROUND

Fracturing operations are conducted in a well to improve the flow of production fluid from a surrounding formation into a wellbore. A variety of fracturing techniques can be employed and involve pumping a fracturing fluid downhole and into the surrounding formation to ultimately improve the flow of production fluids through the formation and into the wellbore. If sand control is required, a separate sand control completion is deployed in the wellbore in an additional procedure to facilitate removal of particulates from produced fluid.

SUMMARY

In general, the present invention provides a multi-stage well treatment system having a plurality of packers and a plurality of flow valves. The multi-stage well treatment system can be moved downhole in a wellbore and actuated to isolate a plurality of sections along the wellbore for treatment. The system and methodology enable treatment, e.g. fracturing, of select sections via the flow valves. However, the flow valves also are used to establish a permeable, stabilized pack surrounding each flow valve in the annulus of each section.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:

FIG. 1 is a schematic front elevation view of a multi-stage well system deployed in a wellbore, according to an embodiment of the present invention;

FIG. 2 is a schematic illustration of one example of the multi-stage well system in which permeable, stabilized packs have been formed in a plurality of isolated sections of the wellbore, according to an embodiment of the present invention;

FIG. 3 is a flowchart illustrating a procedure for using the multi-stage well system, according to an embodiment of the present invention; and

FIG. 4 is a flowchart illustrating another aspect of using the multi-stage well system, according to an embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

The present invention generally relates to a system and method for facilitating well treatments, e.g. fracturing treatments, and for placing permeable, stabilized packs at a plurality of isolated sections along the wellbore. Generally, a multi-stage well system is run into a wellbore and actuated to isolate a plurality of sections along the wellbore. The multi-stage well system comprises flow valves arranged so that at least one flow valve is in each isolated section. The flow valves are used to inject treatment fluid, e.g. fracturing fluid, into each of the sections. However, the flow valves also can be used to direct a proppant into the annulus at each section. The proppant is used to form a stabilized filter pack in each section which functions as a sand control tool.

The multi-stage well system uses a series of isolation devices, e.g. packers, deployed along a tubular structure to form a wellbore completion able to isolate the wellbore sections. The packers can be used in either cased hole or open hole completions to divide the well into manageable sections. These manageable sections enable stimulation, and later production, that is specific to intervals bounded by pairs of packers. The flow valves enable well treatments, e.g. fracturing treatments, and also facilitate creation of the permeable, stabilized packs in the isolated wellbore sections. Generally, each wellbore section has a flow valve positioned along the tubular structure towards the top of the section so that flow through the isolation valve is generally at the upper end of each isolated section when the well system is actuated in a wellbore. During production, production fluids flow from the surrounding formation and through the stabilized pack before entering the completion through the flow valve in each isolated wellbore section.

The multi-stage well system can be used to carry out a variety of well treatment procedures in many types of wells, including vertical wells and deviated wells, e.g. horizontal wells. The well system also can be utilized in many types of well environments, including high-temperature environments, high-pressure environments, H₂S environments, and CO₂ environments. The treatment and production operations can be carried out in sandstone, carbonate, shale, coal or other types of formations.

Referring generally to FIG. 1, one embodiment of a multi-stage well system 20 is illustrated as deployed in a wellbore 22. The well system 20 is designed to carry out well treatment procedures and sand control to facilitate production. As illustrated, multi-stage well system 20 comprises a treatment system 24 that enables multi-stage treatment procedures. The treatment procedures may be followed by production of fluid through a plurality of isolated wellbore sections as production fluid flows from a surrounding formation 26.

In the embodiment illustrated, multi-stage treatment system 24 is formed as part of a single tubing string/completion 30 deployed in wellbore 22 via a conveyance 32, such as tubing. In the example provided, well system 20 is deployed into a generally vertical well extending down from a surface rig 36 or other deployment equipment positioned at a surface location 38. However, well system 20 also can be deployed into deviated wellbores, such as horizontal wellbores.

Multi-stage treatment system 24 comprises a plurality of isolation devices 40, e.g. packers, which can be actuated to isolate sections 42 along wellbore 22. The multi-stage treatment system 24 further comprises a plurality of flow valves 44 with at least one flow valve 44 disposed in each section 42 between adjacent packers 40. Generally, the flow valve 44 in each wellbore section 42 is positioned in the upper portion of the section 42 between adjacent packers 40. The flow valves 44 can be used to direct/inject treatment fluid into each isolated well section 42 during a treatment procedure. For example, flow valves 44 can be used to direct a fracturing fluid into the surrounding formation 26 at each well section 42 to fracture the desired formation zones, thereby promoting the flow of production fluids to wellbore 22. In many applications, the treatment procedure is conducted at individual well sections 42 and progresses from one well section 42 to the next. In a specific application, the multi-stage treatment system 24 is used to conduct a well stimulation procedure by placing the flow valves 44 between external packers 40 at multiple well sections 42. The packers 40 function to divide the well into manageable sections that enable stimulation and production specific to the interval bounded by packers at each end of that interval/well section. Examples of stimulation procedures include matrix stimulation, acid fracturing stimulation, and propped fracturing stimulation.

Upon completion of the treatment procedure, production fluid can be flowed from the various regions of formation 26 into completion 30 via flow valves 44. As described in greater detail below, the inflow of production fluid is filtered by a stabilized filter pack disposed in the wellbore annulus surrounding completion 30 at each wellbore section 42 formed between adjacent packers 40. In the embodiment illustrated, packers 40 and flow valves 44 are mounted on a tubular structure 46. The tubular structure 46 can be used to conduct treatment fluids to flow valve 44 and also to receive production fluids, e.g. oil, through the flow valves 44.

In FIG. 1, packers 40 have been deployed into wellbore 22 and are ready for actuation against the surrounding wellbore wall 48. Depending on the specific application, wellbore wall 48 may be an open wellbore wall or a casing in a cased wellbore. In an open wellbore, packers 40 comprise open hole wellbore packers that can be set against an uncased wellbore. However, packers 40 also can be selected for actuation against a wellbore casing. In the latter example, perforations are formed through the wellbore casing at each isolated wellbore section 42 to enable flow between the formation 26 and wellbore 22.

Referring to FIG. 2, one embodiment of well system 20 is illustrated in greater detail. As illustrated, the packers 40 have been actuated and expanded against wellbore wall 48 to isolate well sections 42. In this embodiment, each flow valve 44 comprises a sliding sleeve 50 that can be actuated between at least an open and a closed position. The sliding sleeves 50 can be moved by a variety of mechanisms, including balls or darts dropped downhole through completion 30 or by shifting tools delivered downhole on an appropriate conveyance. In embodiments that utilize balls to actuate the sliding sleeve, each sliding sleeve comprises a ball seat 52 that works in cooperation with the sliding sleeve 50 to close off flow. The sliding sleeve 50 can be actuated to block flow of fluid from tubing string 30 to the surrounding formation 26 within specific well sections 42. The balls also can be used to block flow along tubing string 30 between isolated well sections 42. In some embodiments, the ball seats 52 have different diameters from one flow valve 44 to the next to enable sequential closing of the flow valves 44 as each sequential well section 42 is treated. It should be noted, however, that other types of valves or mechanisms can be used to control the flow of treatment fluid through the tubing string and into each well section 42.

In the example illustrated in FIG. 2, the flow valves 44 also are used to deliver proppant into the isolated sections 42. For example, the proppant can be delivered into a plurality of annular regions 54 disposed between the tubular structure 46 and the surrounding wellbore wall 48 in isolated well sections 42. The proppant is delivered to form permeable, but stabilized packs 56 that function to perform sand control with respect to fluids flowing in from the surrounding formation 26. The proppant can be delivered downhole via a service tool 58, such as a conduit that can be moved along the interior of completion 30 to selectively deliver proppant to desired flow valves 44. The proppant is delivered from tool 58, through the appropriate flow valve 44, and into the surrounding annular region 54 to form the permeable, stabilized pack 56 in the desired, isolated well section 42. By way of example, the permeable, stabilized packs 56 can be formed from resin coated sand 60. In many applications, the resin coated sand is placed in each section 42 at or below fracturing pressure.

Accordingly, multi-stage well system 24 can be used for well treatment, e.g. delivery of acid or fracturing fluid, and also for sand control. Certain treatment procedures can be combined or sequential. The well system 24 further provides a quick method to place multizone, permeable, stabilized packs that also have the ability to be easily isolated in the future if an undesirable production profile develops. For example, select wellbore sections 42 can be isolated simply by closing the appropriate flow valve 44.

Once well system 20 is deployed in wellbore 22, the permeable, stabilized packs 56 can be formed in some or all of the annular regions 54. The stabilized packs 56 can be formed in an open hole or a cased hole. In the embodiment illustrated in FIG. 2, for example, the wellbore 22 is cased with a wellbore casing 62 having perforated regions 64 through which fluid is communicated between formation 26 and wellbore 22 during injection or production of fluids. In each isolated section 42, the flow valve 44 is generally located at the top of the isolated section, and the perforated regions 64 are generally located at a bottom end of the isolated section to allow the stabilized pack 56 to better remove particulates as fluid flows through a substantial portion of the stabilized pack.

The well system 20 can be used in a variety of well treatment and production applications. In one application example, the treatment string/completion 30 is initially deployed in wellbore 22, as illustrated by block 66 in the flowchart of FIG. 3. Once deployed to a desired location in the wellbore, well sections are isolated along wellbore 22 via packers 40, as illustrated by block 68. At this stage of the process, an initial treatment procedure can be carried out, as illustrated by block 70. The treatment procedure may comprise injecting an acid or a fracturing fluid at each well section 42 via the flow valve 44 located in that specific well section. Additionally, a packing procedure can be carried out in which the permeable, stabilized packs 56 are formed in each well section 42, as illustrated by block 72. In some applications, the fracturing and packing procedures may be combined. The stabilized packs 56 may be formed from resin coated sand delivered to the desired flow valves 44 and isolated sections 42 via service tool 58.

After completing the desired well treatment and the deposition of permeable, stabilized packs 56, a desired formation fluid can be flowed into wellbore 22 and into tubing string 30 through stabilized packs 56, as illustrated by block 74. The stabilized packs 56 filter the inflowing fluid, thus removing particulates from the fluid. After flowing through stabilized packs 56, the formation fluid moves into completion 30 through the appropriate flow valve or flow valves 44 in each isolated section 42. Over time, if one or more of the isolated sections 42 begin producing in an undesirable manner, flow through that particular stabilized pack 56 and isolated section 42 can be reduced or blocked. For example, the flow valve 44 in each isolated section 42 can be used to restrict or close off flow through that section as desired to improve overall production, as illustrated by block 76. Undesirable production in one or more of the well sections 42 may result from the production of gas, water or other undesirable fluids at some point during the life of the well.

Depending on the environment and the completions used to produce fluids from formation 30, the procedures for stimulation/treatment and production can be adjusted. In FIG. 4, another example of a procedure for treating a well and controlling sand during production from the well is illustrated in flowchart form. In this example, the well is initially prepared, as illustrated by block 78. Preparation of the well may involve drilling the well, casing the well, removing an old completion from an existing well, reducing the amount of completion skin to provide each interval/section with an opportunity to be produced to its full capacity, or conducting other procedures designed to facilitate well treatment and production. The well may be prepared, for example, in sand bodies of multiple low-pressure, weak formations. The well also may be prepared in mature fields that are intended for production from multiple zones via an artificial lift mechanism, such as a high rate electric submersible pumping system.

Once the wellbore is prepared, perforations 66 are formed in each of the well sections 42, as illustrated by block 80. The perforations 66 also can result from re-perforation by forming, for example, oriented gravel pack perforations into the plane of fracture. Subsequently, additional preparatory procedures may be conducted to prepare the wellbore for receipt of well system 20, as illustrated by block 82. For example, when well sections are thin or open hole completions are utilized, an optional procedure may be employed to squeeze well intervals with resin to consolidate the formation. Pressure tests are then performed on the intervals subjected to resin consolidation.

Following any additional preparatory procedures, the multi-stage well system 20 is run in hole, as illustrated by block 84, and the packers 40 are set to isolate well sections 42. A treatment procedure can then be performed in each isolated well section 42, as illustrated by block 86. By way of example, the treatment procedure may comprise sequentially performing an acidizing or fracturing procedure at each of the isolated well zones 42. The well sections 42 are then filled with, for example, resin coated sand to establish the permeable, stabilized packs 56, as illustrated by block 88. The resin coated sand is allowed to reach a required minimum strength, and a final well clean out can be conducted, as illustrated by block 90.

A final completion is then run downhole, as illustrated by block 92. The final completion may comprise a variety of production related completions, including completions designed for artificially lifting production fluids to a desired collection location. For example, an electric submersible pumping system can be delivered downhole to pump the fluids that collect within the well system 20. With the final completion in place, the well can be placed on production to deliver production fluids to the desired collection location, as illustrated by block 94. During production, the flow valves 44 can be used to reduce or stop fluid flow through well sections 42 that experience undesirable water cut or gas influx.

As described above, well system 20 can be constructed in a variety of configurations for use in many environments and applications. Additionally, the size and arrangement of the components can be adjusted according to the environment and according to treatment or production parameters. A variety of packers or other isolation devices can be used in both open hole and cased hole applications. Also, various types of flow valves 44 can be used to direct proppant and various treatment fluids outwardly or to conduct the inward flow of production fluids. Furthermore, the permeable, stabilized packs 56 can be formed with a variety of proppants, additives and materials capable of readily forming multiple permeable, stabilized packs.

Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims. 

1. A well system, comprising: a tubular structure deployed in a wellbore; a plurality of packers mounted on the tubular structure and positioned for actuation in an annulus surrounding the tubular structure to divide the wellbore into isolated sections; a plurality of flow valves arranged on the tubular structure to provide at least one flow valve in each isolated section to control flow between an interior of the tubular structure and the annulus, wherein the flow valves comprise a ball seat; and a stabilized filter pack disposed in the annulus at each isolated section, the stabilized filter pack being formed of a resin coated sand.
 2. The well system as recited in claim 1, wherein the plurality of flow valves comprises a plurality of sliding sleeves.
 3. The well system as recited in claim 1, wherein the resin coated sand is disposed in each isolated section between the flow valve and a surrounding casing having a perforated region positioned to allow fluid communication between the annulus and a surrounding formation.
 4. The well system as recited in claim 1, wherein the resin coated sand is placed at or below fracturing pressure.
 5. The well system as recited in claim 1, wherein each flow valve comprises a ball seat.
 6. The well system as recited in claim 1, wherein each flow valve can be selectively closed to block flow between the annulus and an interior of the tubular structure.
 7. The well system as recited in claim 1, wherein the plurality of packers comprises open hole packers.
 8. A method to improve production from a well, comprising: forming a tubular structure with a plurality of packers and a plurality of flow valves, the plurality of packers creating sections for isolation along the tubular structure, the plurality of flow valves being placed such that at least one flow valve is in each section between adjacent packers, and wherein the flow valves comprise a ball seat; deploying the tubular structure in a wellbore; isolating the sections along an annulus surrounding the tubular structure; performing a fracturing procedure at each section by delivering a fracturing fluid down through the tubular structure and out through a flow valve at each section; and using the plurality of flow valves to deliver a proppant to each section to form a permeable, stabilized pack that performs sand control.
 9. The method as recited in claim 8, wherein isolating comprises actuating a plurality of packers.
 10. The method as recited in claim 9, wherein actuating comprises actuating the packers against a well casing having perforations in each section.
 11. The method as recited in claim 8, wherein using comprises filling the annulus in each section with the permeable, stabilized pack until the permeable, stabilized pack fills the space between the flow valve in each section and a surrounding casing having a perforated region.
 12. The method as recited in claim 8, wherein using comprises creating the permeable, stabilized pack with resin coated sand.
 13. The method as recited in claim 8, further comprising flowing a production fluid from a surrounding formation, through the permeable, stabilized pack, and into the tubular structure through the flow valve in at least some of the sections.
 14. The method as recited in claim 8, further comprising selectively closing selected flow valves.
 15. A well system, comprising: a well string having a multi-stage fracturing system deployed in a wellbore to fracture a plurality of sections along the wellbore, the multi-stage fracturing system having packers that can be actuated to isolate the plurality of sections and flow valves disposed between the packers, and wherein the flow valves comprise a ball seat; and a permeable, stabilized pack disposed in each of the plurality of sections via the flow valves.
 16. The well system as recited in claim 15, wherein the permeable, stabilized pack comprises resin coated sand.
 17. The well system as recited in claim 15, wherein each flow valve may be individually shifted between open and closed positions.
 18. The well system as recited in claim 17, wherein each flow valve comprises a sliding sleeve.
 19. A method, comprising: constructing a multi-stage fracturing system having packers and flow valves disposed between the packers to create a plurality of sections, and wherein the flow valves comprise a ball seat; deploying the multi-stage fracturing system in a wellbore; actuating the packers to isolate the plurality of sections; and using the flow valves to deliver a fracturing fluid to each section and to deliver a proppant to each section for forming a permeable, stabilized pack in an annulus at each section.
 20. The method as recited in claim 19, further comprising sequentially fracturing each section.
 21. The method as recited in claim 19, further comprising producing a fluid at each section by flowing a production fluid from a surrounding formation, through the permeable, stabilized pack, and into the multi-stage fracturing system.
 22. The method as recited in claim 19, wherein using comprises forming the permeable, stabilized pack from resin coated sand. 